If you right-click on a worksheet tab at the bottom of a workbook, you
will usually see a "Hide" and "Unhide" option that will allow you to hide
or unhide a sheet.

If you select the "hide" option, you can mark the worksheet you clicked on
as hidden. If there are no worksheets currently hidden, the "unhide" option
will be grayed out. If it isn't grayed out, one or more sheets are hidden and
you can choose to unhide a hidden sheet.

But, when I received
a "no sheet named" error
message because the case of letters I was using for a sheet name didn't
match the all uppercase letters of the actual sheet name when I tried to
access a value from a hidden worksheet in a Python script, when I right-clicked
on a worksheet tab at the bottom of the window
Microsoft Excel for Mac 2016 on my
MacBook Pro laptop,
the Hide and Unhide options were both grayed out. And when
I clicked on Format and selected Sheet from the menu bar at
the top of the Excel window, Hide and Unhide were greyed out.

I knew the sheet was present and where the value I was looking for
was located, though the workbook was created by someone else, because
I could see a defined name for the value pointing to the location
when I clicked on Insert, selected Name, and then
Define. I saw the defined name I was interested in pointing
to =REFERENCE!$L$33. When I modified my script to use
the correct case for the sheet name, I was able to obtain the value.
But when I also included some code to view the visibility setting
for the sheet, I saw the visibility value listed as "1".

The text:u before the value of the cell indicates the cell
holds a text value with the text encoded in the
Unicode
standard. If I use the following print statement, I would only see
CRQ1222539 after the equals sign.

print "Value =", theValue.value

The workbooks I receive are created by others using Excel on Microsoft Windows
systems. When I open them on my Mac, I see the message "This workbook
contains macros. Do you want to disable macros before opening the file?" The
default option is "Disable Macros", but I normally choose "Enable Macros".